(a) Technical Field
The present disclosure relates to a sensorless control method for a motor and a system using the same, and more particularly, to a sensorless control method for a motor and a system using the same that may stably perform sensorless control in an ultra-high-speed driving region of a motor by adding a control model based on iron loss of the motor to a back electromotive force (back EMF) observer, and by obtaining an accurate electrical angle error based on the iron loss through the control model.
(b) Description of the Related Art
As is known in the art, a motor applied to an electrical turbocharger is typically very small and thus may be greatly influenced by characteristic loss thereof. Accordingly, while the motor is driven by a conventional sensorless control method, an electrical angle error thereof increases in an ultra-high-speed driving region, and thus, the motor is not able to be controlled according to an accurate angle, thereby resulting in an uncontrolled situation.
Referring to FIG. 1, which illustrates a controller for a typical permanent magnet electric motor, a sensorless control method observes the back EMF using a measured phase current, d-axis, q-axis voltage, and current commands estimated from the measured phase current to obtain an electrical angle error (Δθ). A phase-locked loop (PLL) controller is used to change the obtained electrical angle error to zero. Estimated angular velocity information may be obtained from output of the phase-locked loop controller in which the obtained electrical angle error is eliminated, and it may be used in a vector control of the motor.
To obtain an accurate electrical angle error, it is necessary to determine the back EMF, and the determination of the back EMF may be obtained from the motor model. Generally, a motor model which does not consider iron loss is used, which is not suitable for controlling an ultra-high-speed motor, at which significantly iron loss occurs. Thus, a large electrical angle error is caused when controlling the ultra-high-speed motor, making the conventional sensorless control method unstable because of the large electrical angle error that results. Therefore, it is difficult to perform the sensorless control in an ultra-high-speed driving region of about 50,000 rpm or more.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure, and therefore, it may contain information that does not form the conventional art that is already known in this country to a person of ordinary skill in the art.